WALL EFFECTS IN THE PYROLYSIS OF DIETHYLETHER - CASE OF HETERO-HOMOGENEOUS PYROLYSIS AT 500-DEGREES-C

The pyrolysis of diethylether has been studied at 500°C and 50 Torr initial pressure in packed vessels (surface‐to‐volume ratio 11 cm−1). In untreated vessels the reaction appears to be essentially homogeneous as reported before. On the contrary, it is very sensitive to the walls of PbO‐coated or NaOH‐treated vessels. Thus most of the initial rates of product formation are increased in the PbO‐coated vessel and decreased in the NaOH‐treated vessel. The efficiency of the walls has been monitored for several weeks and was shown to decrease slowly with the vessel aging time. These phenomena are interpreted in terms of a free‐radical chain mechanism in which a part of the initiation or termination steps occurs at the walls, the propagating steps being homogeneous. The present work clearly proves the existence of hetero‐homogeneous chain reactions at 500°C. This new class of reaction could be of practical interest in the design of industrial reactors. Copyright © 1979 John Wiley & Sons, Inc.